Among hitherto known methods for forming pits and projections in a predetermined target object such as an optical disc, a master disc for manufacturing an optical disc and a light emitting element having a light emitting surface formed with pits and projections is a method in which a photoresist is used as described, for example, in JP 7-161080 A. To be more specific, this method comprises an application step in which a photoresist is applied to a master disc, a light exposure step in which the photoresist is exposed to a laser beam, a development step in which an exposed portion is removed with a developing solution to form predetermined recessed portions, an etching step in which a reactive ion etching (hereinafter referred to as “RIE”) is performed to etch the master disc, and a stripping step in which a residual resist is stripped off, whereby pits and projections are formed in the master disc.
In this method in which pits and projections are formed by etching, failure to have recessed portions neatly formed on the photoresist as a mask for use in etching would disadvantageously result in failure to neatly form pits and projections in the master disc. To address this problem, a method has been proposed in which the processing quality of recessed portions formed on the photoresist is inspected after exposure and development of the photoresist.
However, according to the prior art technique as described above, the processing quality inspection should be performed after the development step, and thus the result of inspection cannot be utilized as feedback for processing (processing of recessed portions by exposure to light) of the product being inspected. That is, if the amount of light exposure of a portion corresponding to the recessed portion becomes out of desired values halfway through the exposure to light for some reason, then the subsequent light exposure will not be performed properly, and all the recessed portions formed in portions in which light exposure has been performed improperly will disadvantageously become defective.